Voltage multiplication apparatus



FIGQI.

Feb. 24, 1959 MR. CLELAND 2,875,394

VOLTAGE MULTIPLICATION APPARATUS 7 Filed Oct. 29, 1956 5 Sheets-Sheet l R-F GENERATOR Feb. 24, 1959 M. R. CLELAND 2,875,394

VOLTAGE MULTIPLICATION APPARATUS Filed Oct. 29, 1956 5 Sheets-Sheet 2 ccQ w 15 0533 CD MP Feb. 24, 1959 M. R. CLELAND 2,875,394

VOLTAGEMULTIPLICATION APPARATUS Filed Oct. 29, 1956 FIGS 5 Sheets-Sheet 3 I l n I K I I l I I l l l I I I I I I I I I I I 1 I I l 1 4 I v Feb. 24, 1959 M, R, CLE LAND 2,875,394

VOLTAGE MULTIPLICATION APPARATUS 5 Sheets-Sheet 4 Filed Oct. 29, 1956 Feb. 24, 1959 M. R. CLELAND VOLTAGE MULTIPLICATION APPARATUS 5 Sheets-Sheet 5 Filed Oct. 29, 1956 QUE 'wgw

VOLTAGE MULTIPLICATION APPARATUS,

Marshall R. Cleland, Rock Hill, Mo., assignor, by mesne assignments, to Radiation Dynamics, Inc., New York,-

N. Y., a corporation of New York Application October 29, 1956, Serial No. 618,862

22 Claims. (Cl. 321-15) This invention relates to voltage multiplication apparams, and more particularly to voltage multiplication appar'atus which provides a substantially constant highvoltage D. C. output potential.

Among the several objects of the invention may be noted the provision of voltage multiplication apparatus which operates from an A. C. supply and supplies a substantially constant D. C. output potential of the order'of one million or more volts at improved D. C. output current levels; the provision of such apparatus which has a high efliciency of voltage multiplication; the provision of apparatus of the class described which may conveniently incorporate an accelerator tube for the production of high energy ion or electron beams; the provision of such apparatus in which the conventional type of filter condenser is eliminated; and the provision of voltage multiplication apparatus which is compact in size and economical in cost. Other objects and features will be in part apparent and in part pointed out hereinafter.

Within the past few years there has been a growing need for a compact, efiicient and economical source of high-voltage D. C. which would provide potentials in the order of a million or more volts and with such power capabilities that current in the order of l to 10 milliamperes could be supplied. One of the most promising approaches toproviding a source of such high potential and current capabilities has been the use of cascaded rectifiers. By interconnecting these rectifiers in a circuit which supplies each such rectifier from a single source of relatively low A. C. potential and effectively connects the D. C. output voltages thereof in series, a rectifier high-voltage D. C. output potential is provided that is many times the amplitude of the input A. C. potential. The trend has been toward operation at higher frequencies in order to reducethe size and cost of the apparatus. However, the requirements of condensers capable of handling the D. C. potentials and high frequency A. C. current values, and the loss of efficiency relative to the theoretical voltage gain as the number of rectifiers is increased, have sharply restricted the commercial pracsuccessivepairs of corona shields by means of the ca pacitance existing between each of these corona shields and the electrodes.

Theinvention accordingly comprises the constructions hereinafter described, the scope of the invention being indicated in the following claims.

UnitedStates Patent ice In the accompanying drawings, in which several of various possible embodiments of the invention are illustrated, Y

Figs. 1 and 2 are side and front end elevations, respectively, of a voltage multiplication apparatus of the present invention, with various parts broken away and shown in section;

Fig. 3 is an enlarged cross section taken on line 3- of Fig. 1;

Fig. 4 is a longitudinal cross section taken on line 44ofFig.1;

Fig. 5 is a view of an accelerator tube component of the apparatus of the present invention; i

Fig. 6 is a schematic representation of .the electric cir-.- cuitry of the apparatus of- Figs. 1-4;

Fig. 7 is a view similar to Fig- '1, showing an alternate. embodiment of the present invention; 1

Fig. 8 is a schematic representation of the electric circuitry of the apparatus of Fig. 7; and Fig. 9 is a schematic representation .of' the. physical. layout and electric circuitry of still another embodimentof the present invention.

Corresponding reference characters indicate corree spond'ing parts throughout the several views of the drawings.

Referring now more particularly to Figs. l-S, an electrically grounded, heavy steel, cylindric, gas-tight pressure container is indicated at reference numeral 1. This container includes a pair of end closures or covers 3 and 5 bolted to a body portion 7 of thecontainer. A pair of trunnions 9 is provided for mounting the con tainer 1 so as to permit movement about the axis of the trunnio'ns. Enclosed within container 1 are a number of cascaded rectifier units (constituted by one or two diode vacuum rectifier tubes V1 to V36), a pair of opposed metallic electrodes or shells E1 and E2, an

accelerator tube AT, inductor I, and various associated components. The electrodes E1 and E2 are mechanically mounted within container 1 by means of insulated mounting brackets B1, B2 and B3 which space the exterior surfaces of these electrodes away from the interior of con tainer 1 and each other. The edges of each of these shells E1 and E2 are rounded and smooth as indicated at EEl and EEZ. A generally C-shaped smooth length of metal tubing TG is mounted on brackets B1, B2 and B3 between the electrode edges BB1 and -EE2. 'As tubing TG is directly connected to the closure 3 by the conducting portion of bracket B3, it is at groundpotential; Thus, the electrodes El and E2 are insulated from each other and container 1, while tubingTG is grounded. p

Closure -5 carries on its inner surface two supporting brackets B4 and B5 to which are aflixed a pairof fcentrally disposed I-beams IE1 and IE2 made out ofplastic or some other suitable insulating materiaL' Positioned between the inner'fiange surfaces of 'each of thebeams and supported thereby are the vacuum rectifier tubes V1 to V36. They are located in two generally parallel vertical banks and in a generally zig-zag configuration. The cathode of tube V1 is maintained at ground potential by interconnecting the cathode cap of tube V1 via a metal clip CL to the closure 5. Similar metal clips CL me"- chanically support the anode and cathode caps of allthe rectifiers V1 to V36. The clipsupporting the anode cap of V1 is electrically connected by a cross bolt CB to the clip supporting the cathode cap of V2. In alike manner, the anode and cathode caps of V3'an'd V4, respectively, are mechanically supported and electrically interconnected. 1 T: In order vto complete a series-connected anode-tocathode. circuit between the cascadedrectifiers Vlto V36, a number of arcuate sections of metal tubing CS40 to C881 are provided. These sections are positioned parallel to each other about a central longitudinal axis of the container and serve to interconnect electrically in series pairs of end-to-end rectifier tubes which pairs then function as single rectifier units. This is accomplished by mechanically connecting each of the clips CL located inside the flanges of the I-beams B1 and 1132 by means of springs S, brackets B, and screws SC to the upper and lower inner surfaces of each of the nearest corona shields C845 to C877 (Fig. 3). The alternate corona shields C845 to C877 which remain unconnected may be left electrically floating or may be interconnected laterally by a cross bolt to the opposite corona shield which is actually serving as an electrical path between a rectifier anode and the cathode of the next rectifier tube on the other side of the web of the I-beams. Arcuate connector tubing sections CS40 to C843 are grounded (i. e., connected to closure and the remaining sections C878 to C881 are commonly connected to a high-voltage terminal as indicated at reference character HVD. This terminal is constituted by a metallic spinning of dome shape. Dome HVD and the connector sections CS40 to C881 are physically supported by triangularly shaped A plastic beams TBl and TB2, which extend longitudinally of the container.

Two additional plastic supports TB3 and T B4 of similar triangular shape are positioned respectively above and below the outside horizontal sections of beams B1 and IE2 and spaced therefrom by insulating ribs R131 to RB4. Within the two long rectangular box-like spaces thus formed between these ribs RBI, RBZ and RB3, R134, respectively, a number of tubular condenser elements CD are located (Figs. 3 and 4). Each of these condenser elements is made of a ceramic cylinder plated on the opposite end surfaces with a conducting metallic film. These condenser elements are organized in a series-parallel arrangement by stacking a number of them in rows and columns between metal plates MP, to constitute a number of condensers CCA, CCB and CC1 to CC16. These metal plates are respectively connected to each of the adjacent anode-cathode rectifier junctions by means of conducting connectors CN, except for the terminal metal plates MP of CCA and CCB which are connected, as will be described subsequently, to the inductor 1.

Another series of arcuate tubular corona shields CS1 to C839 are physically mounted by means of bolts ET on supports TB3 and TB4. Pairs of adjacent shields CS1 to C836 are commonly connected to each respective anode-cathode rectifier junction. That is, shields C81 and CS2 are connected to the junctions between the anode cap of V1 and the cathode cap of V2, while corona shields CS3 and C84 are connected to the anode-cathode junction between tubes V3 and V4. Shields C833, C834, C837 and C838 are commonly connected to a dome-shaped metallic spinningDl while shields C835, C336 and C839 are similarly interconnected to an identical spinning D2. I

The anode cap of the last rectifier V36 is interconnected to the high-voltage dome or terminal HVD and to an end housing EH of the accelerator tube AT (Fig. 5). This accelerator tube is made up of a series of hollow tubular cylindrical sections GS of glass or plastic, stacked end-to-end and separated by metallic rings MR. Accelerator tube AT is positioned on the central longitudinal axis of container 1 in an elongate rectangular box-shaped space between the opposing surfaces of the inner flanges of beams lBl and IE2, and two plastic spacing ribs RBS and RB6.

, Accelerator tube AT terminates at a flexible metal bellows BL which in turn is joined to an'accelerator tube extension XT. This extension XT extends centrally through the container closure 5 and a conventional gas- -tight sealing unit 8U so as to project through a T connector TC. A hose HS from a vacuum pump is connected to one of the T outlets and another carries a probe PB. The end housing EH includes a conventional electron source, such as a hot cathode, and the usual associated grids and focusing elements. As these are wellknown to those skilled in the art, no detailed drawing or description is included herein. For the same reason and to avoid obscuring any of the essential elements of the present invention, insulated control rods, which serve to adjust the cathode temperature and the relative potentials on the grid and focusing elements, and a compact remotely driven generator for powering the cathode of the electron source are not shown. A series of resistors R are connected between adjacent rings MR to assure a substantially lineal potential gradient between the right, or high-voltage, end of the accelerator tube AT and the left, or ground potential, end thereof.

A radio frequency generator, which supplies A. C. power, preferably of a frequency range in .the order of 2G to 200 kc., is interconnected to the apparatus by coaxial cables CXI and CX2. Any customary coupling method of transferring R.:F. power from the R.-F. generator to inductor I may be employed. The inductor which, for the purposes of the voltage multiplication apparatus of the present invention, serves as the source of A. C. power, has a pair of terminals connected by leads I1 and I2 to electrodes E1 and E2, respectively. In ductor I also has a center tap which is connected via wire CT and a milliammeter MA to ground. A pair of intermediate taps of inductor I are electrically connected as indicated at I3 and I4 to the end plates MP of condensers CCA and CCB.

The voltage multiplication apparatus as illustrated in Figs. 1-5, accordingly, is broadly constituted by an A. C. power source I, supplied with electrical energy from an R.-F. generator and connected to apply an A. C. potential across metallic electrodes E1 and B2. A number of cascaded rectifiers V1 to V36 are series-connected anodeto-cathode between an A. C. neutral or ground (as constituted by the center tap of inductor I) and a high voltage terminal HVD. This terminal is electrically connected to the cathode of an electron source contained within housing EH of accelerator tube AT. This tube is connected between ground and the high-voltage terminal to provide an evacuated lineal path for the electrons emitted from the cathode and accelerated in their course down the tube AT.

The vacuum rectifiers V1 to V36 are organized in a series of rectifier units. One type of unit is made up of single rectifier tubes, i. e., V1 and V36, while the remaining tubes V2 to V35 are paired so that each pair (e. g., V2, V3 and V4, V5, etc.) constitutes a rectifier unit.

It will be noted that the entire D. .C. apparatus (rectifiers, corona shields, condensers and accelerator tube) is mounted on the interior of closure 5 by means of brackets B4 and B5 and that convenient access to the various com ponents of this apparatus can be accomplished merely by unbolting closure 5 and moving it to the left. Asthe spacing and relative placement between the corona shields CS1 to C831, the edges EEI and EEZ, and the interior surface of E1 and E2 are such that clearance is provided, the end closure and the above-noted associated components may be conveniently removed from the normal position wherein these components are nested between the electrodes E1 and B2.

In order to increase the limits of relative potentials, both I). C. and A. C., which may be impressed across various elements of this voltage multiplication apparatus Without sparking or corona discharge, it is preferred that container 1 be filled with some atmosphere other than air, such as sulfurhexafluoride gas at above-atmospheric pressure.

Referring now more particularly to Fig. 6, the electrical circuitry equivalent to the physical structure described above in Figs. 1-4 is schematically illustrated. It will be seen that the A. C. potential which is impressed between electrodes E1 and E2," and which is preferably in the order of 50,000 to 150,000 v. at a frequency of the range of 20 to 200 kc., is supplied by inductor I. A somewhat reduced A. C. potential is applied to condensers CCA and CCB. Thus an A. C. potential exists across each of the rectifier units V2, V3 to V34, V35, this potential being approximately halved on the initial and terminating rectifier units V1 and V36. The interelectrode (anode-cathode) capacities of each of the rectifier tubes are indicated by dashed lines at CV1 to CV36. The stray capacitances which are formed between the various corona shields CS1 to C839 and the domes D1 and D2 are similarly indicated at CESl to CES19.

If the circuitry of Fig. 6 is now considered, eliminating the electrodes E1 and E2, it will be apparent that there are stray capacitances between the corona shields CS1 to C339 and the grounded container, rather than between these shields and the electrodes E1 and E2. As there is effectively a single A. C. input potential connected in parallel via condensers CCA, CCB and CC1 to CC16 across each of the rectifier units and the rectified D. C. outputs thereof are effectively connected in series, a D. C. voltage multiplication takes place, whereby the theoretical no-load output voltage would equal the applied A. C. potential connected across condensers CCA and CCB multiplied by the number of full stages of rectification (i. e., the seventeen rectifier units V2, V3 to V34, V35 and the two single rectifier tube units V1 and V36). In the present instance (that is, without consideration of the electrodes E1 and E2), if the applied A. C. potential across CCA and CCB were 60,000 v. peak, the theoretical D. C. output should be 18 60,000, or 1,080,000 v. However, this theoretical value is not obtained in practice, but instead a sharply decreased D. C. output voltage is obtained. This difference between the theoretical and actual D. C. output voltage is due to a combination of factors. The stray capacitances between the corona shields and ground (in the absence of electrodes E1 and E2) and the interelectrode capacities of the rectifier tubes cause A. C. currents to be drawn through the filter condensers CCA, CCB, CC1 to CC16. These currents produce an A. C. ripple voltage across each filter condenser, which voltage is opposite in phase to the voltage across the inductor. Because of these A. C. displacement currents, the A. C. potential carried by the filter condensers to the rectifier units gets progressively smaller from left to right. These currents also cause dielectric heating in the filter condensers which complicates their design and is a distinct limiting factor in increasing the operating frequency of the apparatus, an increase in operating frequency being desirable in order to obtain high D. C. outputcurrent from the rectifier circuit.

In accordance with the present invention, these disadvantages can be overcome by surrounding the cascaded rectifier units, condensers, corona shields, etc., by curved metal shells or electrodes, as shown at E1 and E2, which are electrically connected to opposite ends of the inductor I. Then the stray capacitances CESl to CES19 terminate at the electrodes El and E2 as indicated in Fig. 6, rather than-at the grounded container 1. Assuming first that the same A. C. potential is impressed across the electrodes E1 and E2 as is applied to condensers CCA and CCB (by moving connections I3 and I4 outward to the ends of the inductor), that component of the A. C. displacement current in the filter condensers CCA, CCB, CC1 to CC16 due to the stray capacitances between corona shields and the grounded container 1 is thereby eliminated, the A. C. ripple across these filter condensers is thereby reduced and the efliciency of voltage multiplication is substantially increased.

If, however, as shown in Fig. 6, a higher A. C. potential is impressed across E1 and E2 ascompared to that coupled to the cascaded rectifiers through CCA, CCB,

CC1 to CC16, the other component of A. .C. displacement current in the filter condensers (i.' e., that due to rectifier interelectrode capacitances). can be completely cancelled by A. C. displacement currents flowing through the capacitances between the corona shields and the electrodes E1 and E2, which currents are now out-ofphase with the rectifier displacement currents. Thus, the entire undesirable elfect of all A. C. displacement currents in the filter condensers, which otherwise impose considerable limitations on the apparatus as noted, is eliminated. j

The optimum value (V of voltage to be applied between electrodes E1 and E2 in order to achieve this cancellation is expressed by:

where V is the peak A. C. voltage applied to the'filter condensers, CV is the eifective interelectrode capacitance across one rectifier unit (two series-connected rectifier tubes) and CBS is the stray shield-electrode capacitance. The D. C. voltage generated bythe apparatus will now be substantially n V (where n is the number of recti fier units, i. e., eighteen in the present illustration). It is particularly desirable thatthese A. C. currents are coupled directly and individually from the electrodes E1 and E2 to each of the rectifier junctions, because in that way each branch displacement current component through the separate rectifier units is compensated at its point of origin and there is no A. C. attenuation'due to A. C. current flow through the series-connected filter condensers CCA, CCB, CC1 to CC16.

As it is important to avoid any A. C. ripple or rider wave on the D. C. output potential, the high-voltage terminal HVD is made neutral as to A. C. In the illustrated apparatus this is accomplished because the A. C. potentials coupled to the domes D1 and D2 are equal in amplitude and opposite in phase, thus effectively placing HVD at an A. C. neutral. It will be understood that other methods of establishing an A. C. neutral at the high-voltage terminal, other than by using the abovedescribed balanced A. C. potentials of domes D1 and D2, may be used. Examples of such otheroutput networks are shown in succeeding embodiments, but additional equivalent methods of establishing such A'. C. neutrals (such as networks of inductances and condensers, or off-centerinductor tapping,-etc.) could be used and will be readily apparent to those skilled in the art. Similarly, input networks other than shown in Fig. 6 and other embodiments disclosed herein are well-known to those skilled in the art and may be used as equivalentsl For this reason, such additional examples of such equivalents are not specifically illustrated. i

As described above, substantial or complete compensation of the A. C. displacement currents in the filter condensers is accomplished by the apparatus of the present invention, which affords an opportunity for a still further improvement of voltage multiplication apparatus, viz., the complete elimination of'the conventional type of'filtei' condensers CCA, CCB and CC1 to'CC16. Because of this complete A. C. current compensation, the capacitances of the filter condensers can be reduced in inverse proportion as the frequency of the A. C. power source is increased, while still maintaining an acceptably high D. C. output current capability and a high efficiency of voltage multiplication. If the operating frequency is sufiiciently high, the stray capacitances CESl to CES19 will function additionally to filter the D. C. output voltage of the rectifier units. Then the'conventional filter capacitors may be removed. Such apparatus isillustrated in Figs. 7 and 8.

The voltage multiplication apparatus of Figst 7 and.

8 is identical to thatillustrated (Figs, .1-6) and described above. with the exception of certain modifications, as follows. The condensers CCA, CCB and CC1 to. CC16 are eliminated. An additional set of corona shields CSA aevasea and CSB are provided, which shields are movable along beams TB3 and T84 so as to provide variable capacitancesbetween each of these shields and the respective adjacent corona shields CSI and CS3, as indicated in dashed lines and at reference characters CEVI and CEV2. Two circular metal plates or elements C1 and C2 are adjustably mounted within domes D1 and D2 to provide independently variable capacitances between these plates and the interior surfaces of the domes as indicated at CEV3 and CEV4, respectively. Also, these plates C1 and C2 are interconnected by an electrical conductor EC via the primary of a transformer T (mounted within the accelerator tube end housing EH), the center tap of which is commonly connected to HVD and the anode of rectifier V36. Another modification is the elimination of the intermediate taps on the inductor I.

The operation of the Figs. 7 and 8 embodiment is likewise similar to that of Figs. 1-6. The A. C. potential capacitively coupled individually to each of the rectifier junctions (via stray capacitances CESl to CES16) provides. the same A. C. input potential across each of the recitfier units except the first and last units which, in this example, have half the A. C. potential of the others. The filtering action of these stray shield-electrode capacitances and the rectifier tube interelectrode capacitances is adequate to provide a substantially constant D. C. voltage of approximately the theoretical value at HVD and with adequate regulation even at the relatively high beam current levels of 1 to 10 milliamperes,

provided the frequency of the R.-F. generator is sutficiently high.

The stray capacitances CEVl and CEVZ are variable to assure the proper A. C. amplitude across tubes V1 and V2, V3. The stray capacitances CEV3 and CEV4 perform an analogous function at the high-voltage (or right) end of the apparatus to assure the proper A. C. amplitude across tube V36 and V34, V35. These actions at the two ends are essentially the same in principle. By varying the dimensions of C1, C2 and/or the relative spacing to D1, D2, the A. C. potentials of D1 and D2 (and therefore of the rectifier junctions V33, V34 and V35, V36, respectively) and at HVD can be balanced and otherwise adjusted. Additionally, the current flowing through conductor EC provides (via transformer T) heater power for the cathode of the electron source, thus eliminating the need for a separate-generator, as used in the preceding embodiment.

A third embodiment of the present invention is illustrated in Fig. 9, wherein .the rectifier units, instead of being physically arranged in a parallel zig-zag configuration, are. positioned coaxially end-to-end. These rectifier units are constituted by single rectifier tubes VEl to VE4.. It is possible to extend this apparatus to any number of rectifier units. The cathode of the first tube VEl is connected to ground through an R.-F. choke RFC. Another choke RFC interconnects the anode of VE4 to a high-voltage D. C. terminal HV. Each of the junctions between the rectifiers V131 and VE4, as well as the cathode and anode caps of VEI and IE4, respectively, is surrounded by a hollow cylindrical corona shield CSC to CSG. A series of hollow cylindrical shells or electrodes ElA, E2A, ElB, B2B and BIG of an increased diameter are coaxially mounted so as to surround CSC to. CSG, respectively. The alternate electrodes ElA, B1B and BIG are connected via I1 to one end of inductor I, while the remaining electrodes E2A and B2B are commonly connected by I2 to the other end of inductor I. The radial spacing between these electrodes and shells can be filled with any suitable gaseous, liquid or solid dielectric material, thus enabling the capacities therebetween and the voltage insulation to be adjusted independently of the physical spacing. The ends of all the corona shields and the electrodes are'to be rounded and smooth to prevent corona discharge or sparking between elements.

As the functions of the five electrodes ElA to B2B and the corona shields CSC to CSG are the same as those of electrodes E1 and E2 and shields CS1 to CS39, respectively, in the preceding embodiment, the operation of the voltage multiplication apparatus of Fig. 9 is similar. It is to be noted, however, that this embodiment is capable of being constructed so as to have a minimum outside diameter and thus have physical dimensions which permit the apparatus to be employed where narrow space limitations would otherwise restrict the use of the preceding embodiments.

The power source for the cathodes of each of these rectifier tubes of the present invention may be an independent battery contained in the cathode housing, or a series of cascaded transformers (similarly located) inductively linked to each other with suitable insulation precautions, or any other equivalent sources of energy known in the art. Such sources may be eliminated entirely if semi-conductor (e. g., germanium or silicon diodes) or dry type (e. g., copper oxide or selenium) rectifier units are employed in place of the vacuum tube rectifiers illustrated herein. Also, if desired, gas-filled rectifiers may be utilized. In the event rectifier units other than vacuum or gas-filled rectifier tubes are used, it is to be understood that the terms anode and cathode as used herein identify the terminals of any such semi-conductor or dry type rectifier units.

The inductor I is preferably of toroidal form in order to minimize its external magnetic field. This field causes eddy currents within the steel walls of container 1 and its covers 3 and 5 which waste R.-F. power. The external magnetic field of the coil may also impede the operation of the acceleration tube by deflecting the elec tron beam from its normally straight path. However, this coil configuration may be changed if the space requirements permit, or structure modifications are made. Regardless of the configuration of the inductor, it is of such inductance that it will resonate in an LC circuit (the capacitance of which is constituted by the interelectrode capacitances of the electrodes attached to the inductor and the container-electrode capacitance which are in parallel therewith) at a frequency substantially equal to that of the A. C. power source.

The elongate tube ET located intermediate the electrode edges EEil and EE2, although not necessary for operation of the apparatus, does perform a desirable function. Its presence modifies the configuration of the electric field existing between these two opposing electrode edges so as to minimize arcing and discharge tendencies therebetween. If desired, additional tubing lengths shaped similarly to that of ET can be interposed between ET and the respective opposing electrode edges to further improve the electric field pattern.

It is to be understood that the electron source could be replaced by an ion source, such as that of the PIG type which supplies positive ions at the high-voltage end of the accelerator tube. To accomplish this, the polarity of the high-voltage terminal must be made positive with respect to ground. If this is desired, then all that has to be done to fully accommodate the present apparatus to this purpose (other than modifying the housing EH to provide the ion supply) is merely to reverse each of the rectifiers V1 to V36 in its respective clips so that the anode of V1 is grounded and the cathode of V36 is connected to the high-voltage terminal, and the other rectifier units are connected anode-to-cathode therebetween.

In view of the above, it will be seen that the several objects of the invention are achieved and other advantageous results attained.

As various changes could be made in the above constructions without departing from the scope of the invention, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

'I claim: v

1. Voltage multiplication apparatus comprising a pair of metallic electrodes, a source of A. C. power connected to said electrodes, a plurality of rectifier units each having'an anode and a cathode, said units being positioned between said electrodes and being series-connected anodeto-cathode between ground and a high-voltage D. C. terminal, and a corona shield connected at each of the electrical junctions thereby formed between said rectifier units whereby an A. C. potential of substantially equal amplitude is capacitively coupled across successive pairs of corona shields via the capacitance thereby formed between said electrodesand said corona shields.

2. Voltage multiplication apparatus comprising a grounded container, a plurality of rectifier units disposed within said container, each of said rectifier units having a cathode and an anode, said units being seriesconnected anode-to-cathode between ground and ahighvoltage D. C. terminal, a corona shield connected at each of the electrical junctions thereby formed between said rectifier units, and a pair of intermediate metallic electrodes interposed between the interior of said container and said corona shields, said electrodes being connected to opposite terminals of an A. C. power source.

3. Voltage multiplication apparatus comprising a grounded container, a pair of opposed metallic electrodes within said container, a source of power connected to said electrodes to supply an A. C. potential therebetween, a terminal electrically connected to said A. C. source at an A. C. potential intermediate that of said electrodes, a plurality of rectifier units each having an anode and a cathode, said units being positioned between said opposed electrodes, said units being series-connected anode-tocathode between said terminal and a high-voltage D. C. terminal,a corona shield connected at each of the electrical junctions thereby formed between said rectifier units whereby an A. C. potential of substantially equal amplitude is capacitively coupled across successive pairs of corona shields via the capacitance thus formed between said electrodes and said corona shields.

4. Voltage multiplication apparatus comprising a grounded container, a plurality of rectifier units disposed within said container, each of said rectifier units having a cathode and an anode, said units being series-connected anode-to-cathode between ground and a high-voltage D. C. terminal, a corona shield connected at each of the electrical junctions thereby formed between said rectifier units, a condenser connected between each set of alternate junctions, and a pair of intermediate metallic electrodes interposed between the interior of said container and said corona shields, said electrodes being connected to opposite terminals of an A. C. power source.

5. Voltage multiplication apparatus comprising a grounded container, a plurality of rectifier units disposed within the container, each of said rectifier units having a cathode and an anode, said units being series-connected anode-to-cathode between ground .and a high-voltage D. C. terminal, a corona shield connected at each of the electrical junctions thereby formed between said rectifier units, a pair of intermediate metallic electrodes interposed between the interior of said container and said corona shields, and an inductor adapted to supply an A. C. potential at opposite terminals thereof and having a grounded intermediate tap, said electrodes being connected to said terminals.

6. Voltage multiplication apparatus comprising a grounded container, an inductor adapted to supply an A. C. potential at opposite terminals thereof, a tap on said inductor connected to ground, a plurality of rectifier units positioned within said container, each of said rectifiers having a cathode and an anode, the cathode of a first of said rectifier units being connected to ground,

the anode of a second of said rectifier units being connected to a high-voltage D. C. terminal, each of said remaining rectifier units being series-connected anode- 1O to-cathode between the anode of said first rectifierunit and the cathode of said second rectifier unit, a corona shield connected at each of the electrical junctions thereby formed, a condenser connected between each set of alternate junctions, a condenser interconnecting said first rectifier anode and one of said inductor terminals, a

condenser interconnecting the 'other of said inductorterminals to the anode of the rectifier unit connected to said first rectifier anode, and a pair of intermediate metallic electrodes interposed between the interior of said container and said corona shields, said pair of electrodes being connected to said inductor terminals.

7. A voltage multiplication apparatus as set forth in claim 6 in which the polarity of each of said rectifier units is reversed by connecting the anode of the first unit to ground and the cathode of the second unit to a highvoltage terminal.

8. Voltage multiplication apparatus comprising a grounded container, a pair of metallic electrodes within said container, first and second rectifier units each having a cathode and an anode, said units being series-connected anode-to-cathode at an electrical junction, a plurality of additional rectifier units each having a cathode and an anode series-connected anode-to-cathode between a junction thereby formed with said second rectifier unit and a.high-vo ltage D. -C. terminal, an inductor adapted to supply an A. C. potential at opposite terminals thereof and having a grounded center tap, a pair of taps on said inductor intermediate said center tap and said inducitor terminals, said inductor terminals being connected to said electrodes, first and second condensers interconnecting the intermediate taps with the first and second said electrical junctions respectively, a plurality of additional condensers, one of said additional condensers connected between each set of alternate electrical rectifier unit junctions, and a corona shield connected at each of the junctions between said interconnected rectifier units whereby an A. C. potential of substantially equal amplitude is capacitively coupled to each of said junctions via the capacitance thereby formed between said electrodes and said corona shields.

9. Voltage multiplication apparatus comprising a grounded container, an inductor adapted to supply an A. C. potential at opposite terminals thereof, a tap on said inductor connected to ground, first and second rectifier units each having a cathode and an anode, the cathode of said first rectifier unit being connected to ground, said units being series-connected anode-to-cathode at an electrical junction, a plurality of additional rectifier units each having a cathode and an anode series-connected anode-to-cathode between a junction thereby formed with said second rectifier unit and a high-voltage D. C. terminal, a corona shield connected at each of the electrical junctions thereby formed, a pair of intermediate metallic electrodes interposed between the interior of said container and said corona shields, said pair of electrodes being connected to said inductor terminals, first and second commonly-connected metallic elements respectively spaced from the corona shields connected to said first and second rectifier unit anodes, and means for independently varying the capacitance between each of said elements and its adjacent corona shield whereby the A. C. potential of these last said corona shields may be made substantially equal to the A. C. potentials of the other corona shields.

10. Voltage multiplication apparatus comprising a grounded container, an inductor adapted to supply an A. C. potential at opposite terminals thereof, a tap on said inductor connected to ground, first and second rectifierfunits each having a cathode and an anode, the anode of said first rectifier unit being connected to a high-voltage D. C. terminal, said units being series-connected anode-to-cathode at an electrical junction, a plurality of additional rectifier units each having a cathode and an anode series-connected anode-to-cathode between a junction thereby formed with said second rectifier unit and ground, a corona shield connected at each of the electrical junctions thereby formed, a pair of intermediate etallic electrodes interposed between the interior of said container and said corona shields, said pair of electrodes being connected to said inductor terminals, first and second commonly-connected metallic elements respectively spaced from the corona shields connected to said first and second rectifier unit cathodes, and means for independently varying the capacitance between each of said elements and its adjacent corona shield whereby the A. C. potential of these last said corona shields may be made substantially equal to the A. C. potentials of the other corona shields.

11. Voltage multiplication apparatus comprising a grounded container, an inductor adapted to supply an A. C. potential at opposite terminals thereof, a tap on said inductor connected to ground, a plurality of rectifier units positioned within said container, each of said rectifiers having a cathode and an anode, the cathode of a first of said rectifier units being connected to ground, the anode of a second of said rectifier units being connected to a high-voltage D. C. terminal, each of said remaining rectifier units being series-connected anodeto-cathode between the anode of said first rectifier unit and the cathode of said second rectifier unit, a corona shield connected at each of the electrical junctions thereby formed, a pair of intermediate metallic electrodes interposed between the interior of said container and said corona shields, said pair of electrodes being connected to said inductor terminals, first and second metallic plates connected to said second rectifier anode and spaced from said electrodes, and means for independently varying the respective effective capacitances established between each of said plates and its adjacent electrode whereby the A. C. potential of saidsecond rectifier anode may be made neutral in relation to ground.

12. Voltage multiplication apparatus comprising an elongate grounded container, a plurality of rectifier units positioned end-to-end within said container and along a longitudinal axis thereof, each of said rectifiers having a cathode and an anode, the cathode of a first of said rectifier units being connected to ground, the anode of a second of said rectifier units being connected to a highvoltage D. C. terminal, each of said remaining rectifier units'being series-connected anode-to-cathode between the anode of said first rectifier unit and the cathode of said second rectifier unit thereby forming a series of electrical junctions, a plurality of hollow corona shields connected at each of said electrical junctions, an intermediate hollow metallic electrode element interposed between the interior of said container and surrounding each of said corona shields, a source of A. C. power adapted to supply an A. C. potential across a pair of terminals, one of said terminals being connected to alternate electrode elements, the remaining alternate electrode elements being connected to the other terminal.

13. Voltage multiplication apparatus comprising a pair of elongate metallic electrodes, a source of A. C. power connected to said electrodes, a plurality of rectifier units each having a cathode and an anode, said units being positioned between said electrodes and being series-connected anode-to-cathode between ground and a high-voltage D. C. terminal, an elongate accelerator tube disposed between said electrodes with its longitudinal axis parallel to a longitudinal axis of said electrodes, opposite ends of said tube being connected to ground and the highvoltage D. C. terminal respectively, and a corona shield connected at each of the junctions thereby formed between said interconnected rectifier units whereby an A. C. potential of substantially equal amplitude is capacitively coupled across successive pairs of corona shields via the capacitance thereby formed between said electrodes and said corona shields.

14. Voltage multiplication apparatus as, set forth in claim 13 in which said rectifier units are disposed in a zig-zag configuration between said electrodes.

15. Voltage multiplication apparatus comprising a grounded container, a plurality of rectifier units within said container, each of said rectifier units having a cathode and an anode, said rectifier units being connected anode-to-cathode between ground and a highvoltage D. C. terminal, a corona shield connected at each of the electrical junctions thereby formed between said rectifier units, a pair of intermediate metallic electrodes interposed between the interior of said container and said corona shields, a source of power connected to said electrodes to apply an A. C. potential thereacross, first and second metallic plates spaced from said electrodes and electrically connected together through the primary of a transformer, said transformer primary having an intermediate tap connected to said high-voltage D. C. terminal.

16. Voltage multiplication apparatus comprising a grounded container, a plurality of rectifier units within said container, each of said rectifier units having a cathode and an anode, the cathode of a first of said rectifier units being connected to one of said terminals, the anode of a second of said rectifier units being connected to a highvoltage D. C. terminal, each of the remaining rectifier units being series-connected anode-to-cathode between the anode of said first rectifier unit and the cathode of said second rectifier unit thereby forming an electrical junction between adjacent rectifier units, a corona shield connected at each of said electrical junctions between said rectifier units, and a pair of intermediate metallic electrodes interposed between the interior of said container and said corona shields, a source of power connected to said electrodes to apply an A. C. potential thereacross, at least two of said corona shields having means associated therewith for independently varying the capacitance between each of the last said shields and its adjacent electrode whereby the amplitude of the A. C. potentials of such shields may be varied.

17. Voltage multiplication apparatus comprising a pair of opposed metallic shells having their respective edges spaced apart, a source of electric power connected to said shells to apply an A. C. potential thereacross, a plurality of rectifier units each having an anode and a cathode, said units being positioned between said shells and being series-connected anode-to-cathode between ground and a high-voltage D. C. terminal, and a corona shield connected at each of the electrical junctions thereby formed between said rectifier units whereby an A. C. potential of substantially equal amplitude is capacitively coupled across successive pairs of corona shields via the capacitance thereby formed between said shells and said corona shields.

18. Voltage multiplication apparatus as set forth in claim 17 which includes at least one elongate metallic element positioned between the spaced apart opposed edges of said shells.

19. Voltage multiplication apparatus as set forth in claim 18 in which the opposing edges of said shells are rounded and smooth and the elongate metallic elements are smooth and tubular.

20. Voltage multiplication apparatus as set forth in claim 19 in which the shells, rectifier units and corona shields are enclosed in a grounded container.

21. In voltage multiplication apparatus including a grounded container, a plurality of rectifier units disposed within said container, each rectifier unit having an anode and a cathode, said units being series-connected anodeto-cathode between ground and a high-voltage D. C. terminal, and a corona shield connected at each of the electrical junctions thereby formed between said rectifier units; a pair of intermediate metallic electrodes interposed between the interior of said container and said corona shields, and an inductor adapted to supply an A. C. potential at opposite terminals thereof, said pair of electrodes being connected to said inductor terminals, the inductance of the inductor and the capacitance between the grounded container and the electrodes and the capacitance between the electrodes forming an LC circuit having a resonant frequency substantially equal to the frequency of said A. C. potential.

22. Voltage multiplication apparatus as set forth in claim 21 which further includes an accelerator tube connected between said terminal and ground and adapted to produce a beam of charged particles, and in which the 0 21619502 [4 inductor is toroidal in configuration whereby eddy currents in the surrounding container and other adjacent metallic components are substantially avoided and deflection of the said beam by the inductor magnetic field is 5 substantially prevented.

References Cited in the file of this patent UNITED STATES PATENTS Walker et a1 Nov. 25, 1952 

